Fluid supply systems are used to deliver lubricants during infeeding of stock material, such as strip metals, to stamping presses and dies. More particularly, pressurized fluid delivery systems are preferred for precise control of lubricant deposits relative to volume and timing in a press cycle. Pressurized fluid delivery systems can deliver lubricants in graduated amounts to suitable applicators such as spray nozzles or rollers that interface with the process material.
A common type of fluid delivery system features pneumatically operated, positive displacement pumps. Fluid is drawn into individual pumps then, by actuation of a control valve, pistons force the lubricant from the pumps into supply lines and to the applicators. This known system suffers from at least two drawbacks. First, the only way of adjusting a dispense volume is by mechanical adjustment of individual pump strokes. These adjustments typically are not graduated, so an operator or user repeatedly must fire and observe each deposit for each pump. Not only is this manual procedure time consuming, it wastes lubricant and must be repeated each time a job is setup.
For example, if the operator is using a roller applicator at the infeeding of the strip material, it is sometimes desirable to have a thicker lubrication deposit on an underside of the strip rather than on top. This helps prevent “slug pulling” or “flipping”—a condition in which “slugs” (the portion of the strip being cut away) adheres to a “punch” (a male cutting die), which causing it to be drawn back out of the “die” (the female cutting die). When this condition occurs, it can create feeding problems and/or undesirable indentions in the material production part. Applying more lubrication on the bottom of the material and less on top helps combat this condition while keeping the die adequately lubricated. In this case, timing may not be as important, but differential distribution is critical. However, achieving such differential distribution is extremely difficult with systems that require mechanical adjustment of individual pump strokes.
A second drawback with typical pressurized fluid delivery systems is the existence of a single timing signal. Such a system fires all pumps at once, which may be undesirable. One processing goal, for example, is to use the least amount of lubricant as possible while evenly distributing the lubricant. An accepted way of accomplishing this goal is to spray the lubricant while the strip is advancing. However, if the user needed subsequent nozzles to reapply lubricant at certain intervals throughout the stamping process, this would likely be done while the strip is at rest. With only a single timing signal from the press, the timing would be set for the subsequent nozzles. The nozzle at the infeed would then spray on the strip while at rest and leave a puddle of lubricant rather than an even film of lubricant.
Although some existing systems have independent controls for individual outlets being served by a pressurized supply, their pressure source is a pneumatically operated diaphragm pump. Pneumatically operated pumps typically consume a significant amount of compressed air, and their compressed air generation is approximately only 15% efficient. Moreover, known compressed air systems require multiple power sources to operate associated equipment (e.g., requiring both electricity and compressed air).
Although all-electric pumps also have been used for fluid delivery, such systems utilize a continuously running delivery in which the only way of regulating fluid delivery is by using metering valves to restrict flow. This has a number of disadvantages. First, precise control of lubricants is not possible with continuously running systems. Second, constant pumping of fluid under pressure tends to heat the lubricant, which may be undesirable due to changed handling and make-up characteristics of the heated lubricant. Third, at no time is a lubricant not being applied in a continuously running delivery. Therefore, if connected to a spray nozzle, a continuously running system creates substantial waste and consequently, housekeeping issues due to the spillage.
What is needed in the industry is a portable pressurized fluid delivery system that provides process operators complete control of lubricant deposits; that can be used with multiple types of applicator devices; and that can store settings used with ancillary equipment in a different process setups.